Update on Regulation of Mould Contamination in Manitoba

Indoor Air Quality & Mould
PEN #5

Manitoba Department of Labour Issues Extensive Mould in Buildings Standard

"The Guidelines for the Investigation, Assessment and Remediation of Mould in Workplaces," released in November 2000 by the Manitoba Department of Labour, is the toughest and most detailed provincial standard yet issued on this subject. Manitoba Labour designed the guidelines to establish the minimum requirements for employers responding to complaints from workers, and for contractors performing cleanup of mould contamination. In addition to having a strong impact in Manitoba, they will undoubtedly have an impact elsewhere as other jurisdictions decide on how to respond to this fast-emerging issue.

The Manitoba guidelines adopt or adapt much of the information and advice given in the Health Canada 1995 publication "Fungal Contamination in Public Buildings: A Guide to Recognition and Management" and the 2000 version of the New York City Protocol. In addition, the guidelines offer a great deal of advice on the interpretation of sample results, and set new standards for conducting mould abatement.

Mould growing unseen under carpet (Godslake, MB).
Mould growing unseen under carpet (Godslake, MB)

Investigating mould growth in buildings

The guidelines begin with an introduction to mould in buildings and the potential health effects of mould exposure. The Health Effects section lists the major classes of mould disease and identifies more susceptible individuals who require particular attention in assessments and remediation. The investigative process is described in detail. Investigations are to include interviews with occupants, a review of building history, visual inspection, intrusive inspections, and air, bulk and swab sampling.

Detailed advice is given on the interpretation of results of air, bulk and swab samples. For interpretation of viable air samples, Manitoba Labour endorses the numerical criteria given in the Health Canada 1993 publication, "Indoor Air Quality in Office Buildings: A Technical Guide." For assessment of ventilation equipment, criteria published by the University of Minnesota are recommended. The Manitoba guidelines also give criteria for the interpretation of swab samples taken on non-porous surfaces.

Mould remediation

The guidelines strongly recommend the disposal of all porous materials and contents (furniture, ceiling tiles, lath and plaster, drywall, carpet, etc.) that have become water-damaged. Only in exceptional cases, and within 24 to 48 hours of wetting, should these materials be considered for drying and disinfecting. Even then, surface sampling is recommended to test the effectiveness of recovery efforts. A technically competent person should evaluate the results to determine whether additional remediation is warranted, or if the porous material can be saved at all.

Mould remediation procedures are given for three levels of work, depending on the extent of mould contamination present:

  • Level 1 - less than 0.3 square metres
  • Level 2 - from 0.3 to 3 square metres
  • Level 3 - greater than 3 square metres

For these procedures, Manitoba Labour adopts the classification strategy given in the 1995 Health Canada publication and the 1993 New York City Protocol, rather than the revised New York City Protocol.

Level 1 (less than 0.3 square metres of mould growth) requires that workers use half-facepiece respirators and gloves, a drop sheet below the work and remove all waste in sealed heavy plastic bags.

Level 2 (from 0.3 to 3 square metres) requires the addition of warning signs, a plastic enclosure to contain the work area built of two layers of 6-mil plastic, use of a HEPA (High Efficiency Particulate Air) filtered vacuum cleaner or HEPA exhaust unit to create negative pressure in the work area, a better grade of respirator filter, protective coveralls, cleaning of the site either with a HEPA vacuum cleaner or with an appropriate disinfectant, and wash facilities in the work area.

Level 3 (greater than 3 square metres) precautions are very similar to those for large-scale asbestos removal. In addition to the Level 2 precautions, all contents in the work area must be pre-cleaned with disinfectant prior to removal, a two-chamber worker decontamination unit must be provided, a full-facepiece respirator is required, and all electrical circuits must be deactivated unless equipped with ground-fault protection. In addition, the Manitoba Level 3 procedures include several requirements not seen in previous versions of mould work practices published by other authorities.

  • Manitoba Labour must be notified in writing, at least five working days prior to the start of work.
  • The enclosure and worker decontamination unit must be inspected at the beginning and end of each workday, and at least once per day on days where there are no shifts.
  • Final air monitoring clearance tests must be taken inside the enclosure prior to it being removed. The concentration of mould in the enclosure must be qualitatively and quantitatively similar to that of outdoor air prior to the site being dismantled.

Level 3 mould remediation in a Northern Manitoba school.
Level 3 mould remediation in a Northern Manitoba school

Undoubtedly, the new Manitoba Labour guidelines will have a significant impact on assessment and remediation of mould in Manitoba. We also expect some impact in other provinces, where procedures released to date have not been as rigorous or detailed.

To receive a copy of the guidelines, contact Manitoba Workplace Safety & Health at 204-945-3446.